Electron discharge tube



Filed June 2'7, 1931 2 Sheets -Sheet l 'NVENMR W W TNESS aci w Oct. 22, 1935. c. J. KAYKO ELECTRON DISCHARGE TUBE Filed June 27, 1951 2 Sheets-Sheet 2 Wzmzss Patented Oct. 22, 1935 UNITED STATES PATENT OFFICE ELECTRON DISCHARGE TUBE corporation of Ohio Application June 27, 1931, Serial No. 547,298

9 Claims.

This invention relates to an electron discharge tube sometimes called a contactless relay.

An electron discharge tube of this type may have a variety of uses and is found of practical 5 value in any'control circuit where the available energy of the controlling source is very small.

For instance, the relay tube may be advantageously used in circuit with a photo-electric cell which circuits are at present known to have a 10 wide range of usefulness.

The main object of this invention is to provide an electron discharge tube of a particular construction that will eilect a substantially complete electrical control of electrons from the cathode 15 to the plate electrode at operating voltages.

A further object of this invention is to provide an electron discharge tube of the grid control type that is capable of stopping electron flow between the cathode and plate electrode with comparatively low grid voltages. In this particular construction to be hereafter more fully described, I have accomplished complete interruption of the plate current with a potential on the grid as low as five volts.

Another object of this invention is to provide an electron discharge tube that is capable by means of grid control, to swing the plate current from zero to its maximum value with a very small change of potential on the grid. In this particu- 30 lar instance, I have secured a change of plate current from zero to 100 milliamperes with a change of .05 volts on the grid.

Other objects and advantages relate to the particular structural details of the tube, the geometric relation of the various elements and their relation to the gas pressure employed, all as will appear more fully in connection with the following description, taken in connection with the accompanying drawings, in which:

Figure l is an elevation view of the tube, partly in section.

Figure 2 is a vertical section view showing the electrode assembly. 45v Figure 3 is a cross sectional view taken along lines 33 of Figure 2.

Figure 4 is a vertical section view taken at right angles to Figure 2.

Figure 5 is a cross sectional view taken along 5 line 5--5 of Figure 2.

Figure 6 is a cross sectional view taken along line 66 of Figure 2.

Figure 7 is a cross sectional view taken along line 'l'l of Figure 2.

The relay tube illustrated in the afore-named 5 drawings follows in a general way, conventional multi-electrode tube construction.

In Figure 1 is shown a bulb l enclosing the electrodes supported from rods mounted in a press 2. Lead-in wires from the electrodes passing through the press are secured to the prongs 8 of base 9 in the usual manner. A more detailed arrangement of the electrodes will be obtained from the subsequent figures of the drawings.

Cathode electrode I0 is shown as a heater type employing a cylindrical shell ll of conducting material and having an electron-emitting coating l2. Heater element l3 may be supported within cylindrical shell H and insulated therefrom by heat resisting insulators l4. Current for energizing the heater I3 is conducted thereto by two short rods I5 and I6 which form extensions of the heater element and also serve as a support for the cathode assembly. In this instance, rod

I5 may be welded to a support rod l1 and rod l6 may be similarly secured to rod l8 imbedded in press 2.

A conductor strip l9 connects the cathode coating I2 to lead-in rod 20 sealed in the press. A grid electrode 2| consists of a wound helix supported on two vertical rods 22 and 23. The wires of the helix are preferably closely spaced as compared to a conventional grid used in an amplifier or detector tube.

The lower ends of rods 22 and 23 are preferably secured to a metallic flanged collar 24, An insulating disk 25 adapted to fit into the flanged portion of collar 24 is provided with an aperture centrally located through which cathode support rod l6 projects thereby concentrically spacing the grid electrode with respect to the cathode. The upper ends of rods 22 and 23 may be secured, as shown, to a circular flanged metalic shield plate 26. Shield plate 26 may be provided with two cup-shaped recesses 21 to accommodate insulating bushings 28.

v The cylindrical plate electrode 29 may, in this instance, be welded to rods 30 and 3|, the upper ends of which are fitted into bushings 28. The

outer flanged portion of shield 26.

in wire to the grid electrode as the grid is electrically connected to the cylindrical shield '32 through the upper shield 26. The entire electrode assembly is given further support by means of a glass bead 31 having imbedded therein rods 38, 39, and 43. Rod 38 is bent upwardly and V 7 may be welded to rod I! while rods 39 and 40 are 20 bent downward and have a horizontal portion which'may be welded to shield plate 26 along grooves El and 42 placed in the shield plate to insure extra stiffness. Another pair of grooves 43 may be provided at right angle to the aforenamed groove to increase the stiffness if desired. d

g The lower extremity of rod I1 is secured to rod 44 sealed in the press and which rod also serves as a lead-in conductor to the heater element;

The lower edge of cylindrical shield 32 is further supported by a rod 45 secured to and in turn Welded to rod 46 sealed in the press. An extension of rod 45 provides a suitable means for.

mounting theflashpan assembly 4?. The flash pan is preferably semi-circular in shape, as shown, and provided with'a small opening 49 on the lower side. This construction prevents the getter material 48 from being deposited on the electrodes during the flashing process.

The electrode assembly, as above described, is mounted in a bulb and the usual exhaust methods are applied. Before sealing the tube, however,

' a gas from the inert or rare gas group as argon,

helium or neon is introduced into the bulb, but

in this instance, I prefer neon at a pressure 01' 100 microns at room temperature. In addition, a sufiicient quantity of mercury is introduced into the tube so that it will maintain its vapor pressure at the operating temperature of the tube.

The operation of the tube is such that when the cathode is heated to operating temperature in the presence of a gas at the above-named pressure for the purpose of supplying a sufficiency of electrons, the plate current rises at once to its maximum value. This value will depend upon the resistance of the plate circuit, the potential on the plate electrode, the potential on the grid electrode, the nature of the gas and on the geometric design of the tube. V

I have found that using a tube of the above construction in'which thergrid wires are wound comparatively close and in which the atmosphere sustained 100 microns of neon gas and using a V 7 plate potential of 125 volts, the maximum plate than five volts negative potential on the grid was current obtainable was 100 milliamperes. Less sufficient to stop the plate current.

I have also found that it is possible to swing the plate current from zero to its maximum value, in this instance, 100 milliamperes, by a very small change of potential on the grid, name- 1y, of the order of .05 volts. I have also Ijound that mercury vapor is desirable as a source 05 ions for this particular tube. However, the

tween said anode and cathode at operating voltpresence of other gases as argon, helium or neon are required as a protective agent for the cathode during the heating up process of the tube. In' the absence of a protective gas, the cathode would be destroyed before the mercury in the tube could build up suificient vapor pressure to limit the flow oi electrons. The protective gas is, therefore, necessary during the time required for the tube to reach its operating temperature.

' Although I have shown and describeda specific tube structure and have specified a particular gas pressure and various operating voltages, it is to be understood that the same were for the purpose of illustration and are'notto be viewed as limitations of my invention, as many changes and modifications may be made by those skilled in the art without departing from the spirit and scopeoi the appended claims.

I claim:

1. An: electron discharge. tube comprising an anode, a cathode, a control grid positioned between said anode and said cathode, a shield grid positioned about said anode, a metallic shield member joining the ends of said control grid and said shield'grid, an ionizable gas within the tube 5 at substantially a pressure of 100 microns of mercury, said control grid having a helical configuration, the turns of which are suiiiciently closely spaced that when energized by a suiiiciently low voltage the flow of current from the cathode to the anode may be completely interrupted.

2'. An electron discharge tube comprising an anode, a cathode, a control grid positioned between said anode and said cathode, a shield grid positioned about said anode, a metallic shield member joining the ends of said control grid and said shield grid, neon gas within the tube at substantially a pressure of 100 microns of mercury, said control grid having a helical configuration, the turns of which are sufficiently closely spaced that when energized by a sufficiently low voltage the flow of current from the cathode to the anode may be completely interrupted.

3. An electron discharge tube comprising an anode, a cathode, a control grid positioned between said anode and said cathode, a shield grid positioned about said anode, a metallic shield member joining the ends of said control grid and said shield grid, mercury vapor and neon gas within the tube at substantially a pressure of 10Qmicrons of mercury, said control grid having a hellcal configuration, the turns of which are sufliciently closely spaced that when energized by a suificiently low voltage the flow of current from the cathode to the anode may be completely inter rupted. V

4. An electron discharge tube comprising an anode, a cathode, a control electrode having a helical portion positioned between said anode and cathode and a tubular portion surrounding said anode, a metallic shield member joiningthe ends of said helical and said tubular portions, and an ionizable gas within said tube at a predetermined pressure capable of producing acurrent flow beage in excess to that provided by thermionic emission alone, said helical portion having its turns in sufficiently closely spaced relation whereby energizing said control electrode with a comparatively low voltage will completely stop the flow of said current. V

5. An electron discharge tube comprising an anode, a cathode, a control electrode having a helical portion positioned between said anode and cathode and a tubular portion surrounding said 7 anode, a metallic shield member joining the ends of said helical and said tubular portions, and mercury vapor within said tube at a predetermined pressure at operating temperature capable of producing a current flow between said anode and cathode at operating voltage in excess to that provided by thermionic emission alone, said helical portion having its turns in sufiiciently closely spaced relation whereby energizing said control electrode with a comparatively low voltage will completely stop the flow of said current.

6. An electron discharge tube comprising a thermionic cathode, an anode, a control grid having a helical portion positioned between said anode and said cathode and a tubular portion surrounding said anode, a metallic shield member joining the ends of said helical and said tubular portions, a low pressure atmosphere of ionizable gas within said tube for producing electrons in number greater than said cathode is capable of producing by thermionic emission alone whereby energizing the anode with a sufficient potential will cause current to flow through said tube in excess to that provided by thermionic emission and whereby energizing said control grid with a sufliciently low voltage will substantially completely stop the flow of said current.

'I. A vapor type tube comprising a cathode and a cylindrical anode and being provided with a vaporizable conducting medium, a control grid for the tube comprising a pair of connected equipotential members, one of which is positioned between said oathode and said anode and the other between said anode and the wall of the tube, said other member being arranged extending above and below said anode. 5

8. An electron discharge tube comprising a cathode, a cylindrical anode, a control grid, said control grid having a pair of connected equi-potential members, one of which is positioned between said cathode and said anode, and the other 10 between said anode and the wall of the tube, said other member being arranged extending above and below said anode, and mercury in said tube adapted to produce a substantially constant vapor pressure at the operating temperature of the tube. 15

9. An electron discharge tube comprising a cathode, a cylindrical anode, a control grid, said control grid having a pair of connected equi-potential members, one of which is positioned between said cathode and said anode, and the other 20 between said anode and the wall of the tube, said other member being arranged extending above and below said anode, mercury in said tube adapted to produce a substantially constant vapor pressure at the operating temperature of the 2 tube, and a rare gas within said tube for maintaining the electron current within the safe current carrying capacity of said cathode until the tube reaches operating temperature.

30 CHARLES J. KAYKO. 

